Outer space gas trapped on Earth in 'buckyballs'
This image shows how extraterrestrial gases such as helium can be trapped inside the fullerene cage. One view shows a broken bond, or open "window," with an atom moving out through window.
HONOLULU, Hawaii (CNN) -- Extraterrestrial gases have been trapped on Earth for millions of years by complex molecular structures known as buckyballs, scientists reported this week.
The discovery offers a new method to trace geological and
biological events linked to colossal meteorite and comet
strikes and strengthens the theory that some terrestrial atmospheric gases and organic compounds originated in space.
"This finding opens new possibilities in looking at the
problem of how planetary atmospheres evolved and maybe even
how life evolved on Earth and perhaps other moons and
planets," University of Hawaii geochemist Luann Becker said
in a statement.
Becker and two colleagues found the trapped extraterrestrial
gases in samples from Denmark, New Zealand and North America
taken from a one-inch (2.5-cm) layer of sedimentary clay that divides the Cretaceous and Tertiary periods.
The clay layer formed about 65 million years ago from the fallout of a massive impact crater that many scientists think set off mass extinctions, including that of the dinosaurs.
The gases and their unusual containers originated in space,
the scientists said in the March 28 Proceedings of the
National Academy of Sciences. An advanced version was posted
on the Internet on Tuesday.
Space helium encased for eons
The trapped gases contain high concentrations of helium 3, a type of helium with only three subatomic particles that's found mostly in space. Helium found on Earth, in contrast, usually has four
sub-atomic particles in its nucleus.
Presumably the buckyballs -- microscopic cages composed of carbon atoms -- came from space as well, considering their helium cargo did. But scientists remain unsure when and where they formed.
Formally known as fullerenes, buckeyballs form under dense pressures and extreme temperatures like those in the pre-solar environment, Becker said. Physicist Robert Poreda of the University of Rochester in Rochester, New York, agrees that fullerenes predate our solar system. He adds that they could have come from a star that predates our sun.
"They may have formed in a high energy plasma related to the early solar nebula or they may have formed prior to the formation of our solar system in the outflow from a 'carbon-rich' giant. Our solar nebula then formed from the remnants of this giant star," he said.
Becker published her findings along with Poreda and Ted Bunch
of NASA's Ames Research Center in Moffett, California.
Becker and Bunch first identified naturally occurring
fullerenes in a meteorite last July. They detected large
buckyballs, some composed of 400 carbon atoms, in pieces of
the 4.6-billion-year-old Allende meteorite that landed in
Mexico decades ago.
Samples from Australia's Murchison meteorite offered
additional evidence of the extraterrestrial origin of
fullerene helium cages.
The Permian/Triassic divide
Becker has expanded the research to include the sedimentary layer that divides the 250-million-year old Permian and Triassic periods. The layer marks a time of much greater biological change than the Cretaceous/Tertiary transition.
The investigation could help explain whether a killer comet or meteor spurred the massive species shakeup. Becker also seeks to find out if fullerenes delivered carbon compounds and other substances necessary for life to emerge.
"We're working on that right now. There's more to come hopefully," she said.
What's a 'buckyball?'
Named for Buckminster Fuller, designer of the geodesic dome,
fullerenes have been the subject of intense study since their
discovery in 1985.
A third form of pure carbon after diamonds and graphite,
so-called buckyballs are composed of carbon atoms that have bonded together into hollow, geodesic "cages."
They possess unusual properties that researchers hope to exploit
in everything from superconductors to superlubricants to
Robert Curl, Harold Kroto and Richard Smalley, who first
produced fullerenes in the laboratory, shared the 1996 Nobel
Prize in chemistry for their work. Since then scientists have
discovered naturally existing fullerenes.
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